It is known to maintain satellites in a defined relative position, for example, relative to the earth. Such relative positions enable the satellite to perform its function, especially to maintain communication links. Thus, it is necessary to equip satellites with position control devices in order to make corrections in all degrees of freedom. For this purpose small propulsion engines are used which make it possible to cause the correction movement by exactly proportioned or dosed impulses. The operation of these small propulsion engines, however, requires fuel which must be carried along by the satellite in a fuel tank. The fuels involved are mostly liquid fuels which supply the propulsion engines with the required fuel through a gas generator.
However, in operating such propulsion plants, care must be taken that the propulsion plants receive only the required fuels which must not contain any foreign gases, because generally propulsion gases are used for driving the fuel out of the tank. However, the propulsion gases can mix with the fuel. Therefore, it is necessary, especially in connection with fuel tanks which make use of the surface tension for transporting the fuel, to take special steps for separating the propulsion gas and the fuel. It has been found that small mesh screens are suitable for this purpose. These small mesh screens are arranged on collecting devices or in collecting vessels in the fuel tanks.
The propulsion engines for controlling the position of satellites must work under zero gravity conditions as well as under conditions in which gravity is effective. Therefore, it is necessary to construct the fuel tanks in such a way that the fuel is available in any conceivable situation. This requirement, however, is not met by conventional fuel tanks.